JPH1152618A - Non-magnetic one-component developer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide yellow developer having excellent OHP transparency, color reproducibility, and transfer property. SOLUTION: In non-magnetic one-component developer to be used for forming a full color image to reproduce a multi-color image, the non-magnetic one- component developer at least includes negative charge non-magnetic toner grain containing binder resin of an acid value of 1-30 KOHmg/g, and compound sorted as pigment yellow 180, roundness of the toner grain is 0.94-1.0, standard deviation of the roundness is 0.045 or less, a weight average grain diameter is 2-9 μm, inclusion of the toner grain having twice or more grain diameter to the weight average grain diameter is 2 wt.% or less in grain diameter distribution of toner, and inclusion of the toner grain of 1/3 the weight average grain diameter or less is 5 number % or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a developer for developing an electrostatic latent image, and more particularly to a non-magnetic one-component developer used for a full-color image forming apparatus such as a full-color electrostatic copying machine and a full-color laser beam printer.

[0002]

2. Description of the Related Art Conventionally, an electrostatic latent image formed on an electrostatic latent image carrier such as a photoreceptor is developed using toner, and this toner image is transferred onto a recording member such as recording paper. Image forming methods for forming images are widely used in copiers, printers, facsimiles, and the like. In recent years, full-color image forming apparatuses that reproduce a multicolor image by superimposing a plurality of color toners have been put to practical use. I have.

In such a full-color image forming apparatus, for example, an electrostatic latent image is formed for each dot on a negatively charged organic photosensitive member by digital writing such as irradiation of a light beam, and this latent image is formed. Is developed in reverse using magenta toner, cyan toner, yellow toner and black toner as required, and a multicolor image is reproduced by superimposing toner images of each color.

The above-described full-color image formation mainly includes a picture,
It is used to reproduce photographs, graphic images, and the like. As described above, a multicolor image is reproduced by superimposing a plurality of color toners. Such a multicolor image is widely used not only for forming an image on recording paper but also for an overhead projector sheet (OHP sheet). For this reason, the toner must have a spectral reflectance corresponding to a desired color, and have excellent translucency without hiding the color of the underlying toner during superposition. Is required. This requirement is particularly remarkable for a light yellow toner.

Conventionally known organic pigments and dyes have been known as colorants used in yellow toners, but each has various disadvantages. For example, since dyes generally exist in a state of being dissolved in a binder resin of a toner, they have excellent light transmittance and color saturation, but have a disadvantage that heat resistance and light resistance are low. I have. Since lightfastness is low and fading due to light occurs, there is a problem that even if an image having excellent chroma is obtained, it cannot be maintained for a long period of time. Further, when heat fixing is performed due to low heat resistance, the dye sublimates in the vicinity of the fixing portion, and there is also a problem that contamination in the apparatus easily occurs. In addition, there is also a problem in that some of them are dissolved in a release agent such as silicone oil applied to the fixing roller, and the image is stained. From such a viewpoint, it is preferable to use a pigment. However, since the pigment has a high cohesiveness and is difficult to be uniformly finely dispersed even in the toner, the hiding power of the toner is increased and the light transmittance is reduced. In addition, when the pigment particles are aggregated, the light scattering by the particles makes it impossible to obtain a spectral reflection characteristic for accurately reproducing the original, and the above-mentioned hiding power causes a sufficient transparency. When used for an OHP sheet, it has drawbacks such as a dark projected image and a low saturation when used for an OHP sheet because it cannot provide light properties. Further, some pigments have low heat resistance and are decomposed during the production of toner or heat fixing.

On the other hand, as described above, a full-color toner is required to have excellent transferability in order to reproduce a multicolor image by superposing toners of respective colors. If the charge amount of the toner is too high, the adhesion of the toner to the photoreceptor becomes strong, and the transferability decreases, and the transferability decreases even if the charge amount distribution of the toner is broad. For this reason, the full-color toner needs to have an appropriate charge amount and charge amount distribution. Such a requirement is particularly remarkable when toner is transferred onto an intermediate transfer member using a transfer roller, toners of respective colors are superimposed on the intermediate transfer member, and transferred onto transfer paper using a transfer roller. It is.

In recent years, miniaturization of a full-color image forming apparatus has been studied. For this purpose, it is necessary to reduce the size of a developing device. This is because a full-color image forming apparatus requires four developing devices each containing a cyan developer, a yellow developer, a magenta developer, and a black developer. In order to reduce the size of the developing device, a non-magnetic 1 that does not require a stirring mechanism between the toner and the carrier
Although a component developing device is advantageous, in the case of a non-magnetic one-component developing device, the carrier is not used, so that the toner is charged by contact with a developer carrying member or a developer regulating member. A characteristic that quickly rises to a high charge amount is required.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a non-magnetic one-component developer for forming a full-color image which has solved the above-mentioned problems.

[0009] That is, an object of the present invention is to provide a non-magnetic one-component developer excellent in translucency and color reproducibility.

Another object of the present invention is to provide a non-magnetic one-component developer having an appropriate charge amount and charge amount distribution.

Another object of the present invention is to provide a non-magnetic one-component developer having excellent transferability even when a multicolor image is formed.

[0012]

According to the present invention, there is provided a non-magnetic one-component developer used for forming a full-color image for reproducing a multicolor image, wherein the non-magnetic one-component developer has an acid value of at least 1 to 30 KOH mg / kg. g of binder resin and a compound classified as Pigment Yellow 180. The toner particles have a circularity of 0.94 to 1.0, and a standard circularity. A deviation of 0.045 or less, a weight average particle diameter of 2 to 9 μm, a content of toner particles having a particle diameter of twice or more the weight average particle diameter in the particle diameter distribution of the toner is 2% by weight or less, and a weight average The content of toner particles of 1/3 or less of the particle size is 5% by number.
The present invention relates to the following non-magnetic one-component developer.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The toner particles of the non-magnetic one-component developer for full color of the present invention contain C.I.
I. Pigment Yellow 180. C. I. Pigment Yellow 180-containing toner exhibits excellent properties in light transmission and color reproducibility. C.I. I. Pigment Yellow 180 is excellent in light resistance and heat resistance, so that it has excellent safety without decomposing to generate harmful substances even when heated during production or fixing of toner. . If the content is too small, sufficient saturation cannot be obtained, and if the content is too large, the influence on the charge of the toner becomes strong. I. Pigment Yellow 180 is contained in the binder resin 100.
It is preferably 2 to 15 parts by weight based on parts by weight.

On the other hand, C.I. I. Pigment Yellow 180
In order to improve the dispersibility in the binder resin of
1.0 to 30.0 KOHmg /
g, preferably a resin having an acid value of 1.0 to 25.0 KOH mg / g, more preferably 2.0 to 20.0 KOH mg / g. This has an acid value of 1.0 KOHmg / g
If it is smaller, the effect of improving the dispersibility becomes small, and 30.0
This is because if the KOH is more than mg / g, the negative chargeability becomes stronger and the change in the charge amount due to environmental fluctuations becomes larger.

The type of the resin is not limited as long as it is a binder resin having such an acid value. For example, styrene-acrylic copolymer resin, polyester resin, epoxy resin and the like can be used. Or mixed and used. Among these resins, a polyester resin is particularly preferable.

In the present invention, a preferred polyester resin comprises a bisphenol A alkylene oxide adduct as an alcohol component as a main component, and a phthalic dicarboxylic acid or a phthalic dicarboxylic acid and an aliphatic dicarboxylic acid as an acid component. It is synthesized by a polycondensation reaction.

As the bisphenol A alkylene oxide adduct, bisphenol A propylene oxide adduct and bisphenol A ethylene oxide adduct are suitable, and it is preferable to use a mixture of these.

The following diols or polyhydric alcohols may be used as alcohol components together with bisphenol A alkylene oxide adducts. Examples of such alcohol components include ethylene glycol, diethylene glycol, triethylene glycol,
Diols such as propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, Pentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-
Examples include pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.

Examples of the phthalic dicarboxylic acids include phthalic dicarboxylic acids such as terephthalic acid and isophthalic acid;
The acid anhydride or the lower alkyl ester thereof can be used.

Examples of the aliphatic dicarboxylic acids usable together with the phthalic dicarboxylic acids include fumaric acid, maleic acid, succinic acid, aliphatic dicarboxylic acids such as alkyl or alkenyl succinic acids having 4 to 18 carbon atoms, and acids thereof. Examples thereof include anhydrides and lower alkyl esters thereof.

In order to adjust the acid value of the resin, a small amount of a polycarboxylic acid such as trimellitic acid may be used as long as the transparency of the toner is not impaired. Examples of such a polyvalent carboxylic acid component include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 2,4-naphthalene tricarboxylic acid, 1,
2,4-butanetricarboxylic acid, 1,2,5-hexanenetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl ) Methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, anhydrides thereof, lower alkyl esters and the like.

The binder resin used for the toner particles of the present invention has a glass transition point of 55 to 75 ° C., preferably 58 to 75 ° C.
70 ° C, softening point 95-120 ° C, preferably 100-
118 ° C., the number average molecular weight is 2500 to 6000, preferably 3000 to 5500, and the weight average molecular weight / number average molecular weight is 2 to 8, preferably 3 to 7. When the glass transition point is low, the heat resistance of the toner is reduced, and when the glass transition point is high, the light transmittance and the color mixing are reduced. When the softening point is low, a high-temperature offset is likely to occur during fixing, and when the softening point is high, the fixing strength is reduced. When the number average molecular weight is small, the toner is easily peeled off when the image is bent, and when the number average molecular weight is large, the fixing strength is reduced. When the weight-average molecular weight / number-average molecular weight is small, high-temperature offset is likely to occur, and when it is large, the light transmittance is reduced.

It is preferable to add waxes such as polypropylene wax, polyethylene wax, carnauba wax and sasol wax to the toner particles.
This is because not only can the offset resistance be improved, but also the problem of toner sticking to the regulating member (blade), the developer carrier (developing roller), etc. in the non-magnetic one-component developing device can be reduced. Particularly, the acid value is 0.
It is preferable to use 5 to 30 KOH mg / g wax from the viewpoint of dispersibility in the binder resin having the above acid value. The addition amount of such a wax is preferably 0.5 to 5 parts by weight, and more preferably 1 to 3 parts by weight based on 100 parts by weight of the binder resin. This is because if the amount is less than 0.5 part by weight, the effect of the addition is insufficient, and if it is more than 5 parts by weight, light transmittance and color reproducibility are reduced.

In the present invention, the toner particles can be produced by a known method, and are not particularly limited. can do. In addition, when adding the yellow pigment in the production process, it is preferable to use a master batch-treated or flushed yellow pigment from the viewpoint of improving the dispersibility.

The volume average particle diameter of the toner particles according to the present invention is preferably adjusted to 2 to 9 μm, more preferably 2 to 7 μm, from the viewpoint of high definition reproducibility of an image. Further, toner particles having a content of toner particles having a particle diameter of at least twice the volume average particle diameter of 2% by weight or less, preferably 1% by weight or less, and having a particle diameter of 1/3 or less of the volume average particle diameter Is required from the viewpoint of narrowing the charge amount distribution of the toner and preventing fogging.

The particle size and the particle size distribution of the toner particles were measured using a Coulter Multisizer (manufactured by Coulter Counter Co.) with an aperture diameter of 50 μm.

The toner particles according to the present invention must have a circularity (average circularity) of 0.94 to 1.0 and a standard deviation of the circularity of 0.045 or less. . This is because when the circularity is smaller than 0.94, the electrostatic adhesion of the toner particles to the image carrier and the intermediate transfer member becomes strong, so that transfer failure is likely to occur. If the standard deviation of the circularity is larger than 0.045, the variation in the charge amount of each toner particle becomes large, which causes fogging and transfer failure. Furthermore, from the viewpoint described above, the circularity is preferably 0.945 to 0.945.
0.99, more preferably 0.95 to 0.98,
The standard deviation of the circularity is preferably 0.040 or less, more preferably 0.035 or less.

The degree of circularity is represented by (perimeter of equivalent circle / perimeter of particle projected image) and is represented by a flow type particle image analyzer (F
PIA-1000: manufactured by Toa Medical Electronics Co., Ltd.) in an aqueous dispersion system.

The circularity of the toner particles and the standard deviation thereof can be controlled by the production conditions of the toner particles. For example, in the kneading and pulverizing method, toner particles are produced through a raw material mixing step, a melt kneading step, a pulverizing step, and a classification step. At this time, the degree of circularity and the like can be controlled by using a pulverizing device that can make the particles to be pulverized into a sphere as a pulverizing device used in the pulverizing step. Examples of such a pulverizer include an innomizer system (manufactured by Hosokawa Micron), a crypton system (manufactured by Kawasaki Heavy Industries, Ltd.), and the like. The degree of circularity and the like can be controlled by using a classifier capable of spheroidizing particles to be treated as a classifier used in the classifying step. Examples of such a classifier include a teaplex classifier (manufactured by Hosokawa Micron Corporation).

Further, the degree of circularity and the like may be adjusted by treating the toner particles obtained through the raw material mixing step, the melt kneading step, the pulverizing step and the classifying step with a surface reforming device. Examples of such a surface reforming apparatus include a surface modification using a high-speed airflow impact method such as a hybridization system (manufactured by Nara Machinery Co., Ltd.), a cosmos system (manufactured by Kawasaki Heavy Industries, Ltd.), and an innomizer system (manufactured by Hosokawa Micron Corporation). Equipment, surface reforming equipment using dry mechanochemical method such as mechano-fusion system (manufactured by Hosokawa Micron), mechano mill (manufactured by Okada Seiko), surface reforming equipment using hot air current reforming method such as surf-fusing system And a surface modification apparatus to which a wet coating method such as Dispercoat (manufactured by Nisshin Seifun KK) and Coatmizer (manufactured by Freund Corporation) is applied.

In the present invention, it is preferable to externally add 0.1 to 3% by weight of inorganic fine particles to the toner particles from the viewpoint of improving fluidity and the like. As such inorganic fine particles, silica, titania, alumina, strontium titanate, tin oxide, zinc oxide and the like can be used alone or in combination of two or more. It is preferable to use inorganic fine particles that have been surface-treated with a hydrophobizing agent from the viewpoint of improving environmental stability. Further, other than such an inorganic oxide, resin fine particles of 1 μm or less may be externally added. The non-magnetic one-component developer of the present invention has a structure in which a blade as a developer regulating member is pressed against a developing sleeve as a developer carrier, particularly from the viewpoint of miniaturization of a full-color image forming apparatus. It is preferable to use a non-magnetic one-component developing system in which the toner is charged when the toner passes through the regulating portion.

[0032]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited thereto. The binder resins used in the following examples and comparative examples are as follows.

(Production Example of Polyester Resins A to G) In a glass four-necked flask equipped with a thermometer, a stirrer, a falling condenser, and a nitrogen inlet tube, an alcohol component and an acid component in the molar ratios shown in Table 1. Together with a polymerization initiator (dibutyltin oxide). This was reacted by heating in a mantle heater with stirring under a nitrogen atmosphere to obtain a number average molecular weight (Mn) shown in Table 1.
Polyester resins A to G having a weight average molecular weight / number average molecular weight (Mw / Mn), glass transition point (Tg), softening point (Tm), acid value and hydroxyl value were obtained. Each of the obtained polyester resins was roughly crushed to 1 mm or less and used in the production of the following toner. In Table 1, PO represents polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane, and EO represents polyoxyethylene (2,2).
0) -2,2-bis (4-hydroxyphenyl) propane, GL is glycerin, TPA is terephthalic acid,
TMA represents trimellitic acid and FA represents fumaric acid.

[0034]

[Table 1]

The molecular weight is determined by gel permeation chromatography (807-IT; manufactured by JASCO Corporation).
And using tetrahydrofuran as a carrier solvent, the molecular weight was determined in terms of polystyrene.

The glass transition point was measured by a differential scanning calorimeter (DSC-
200; manufactured by Seiko Denshi Co., Ltd.)
0 mg was measured, and alumina was used as a reference, and the shoulder value of the main endothermic peak in the range of 30 to 80 ° C. was taken as the glass transition point.

Regarding the softening point, a flow tester (CF
T-500; manufactured by Shimadzu Corporation), a sample of 1.0 g was measured using a 1.0 mm × 1.0 mm die under the conditions of a temperature increase rate of 3.0 ° C./min and a load of 30 kg. Is the softening point when 1/2 flows out.

The acid value was represented by the number of mg of potassium hydroxide required to dissolve the weighed sample in an appropriate solvent and neutralize the acidic group using an indicator such as phenolphthalein.

The hydroxyl value was represented by the number of mg of potassium hydroxide required for treating a weighed sample with acetic anhydride, hydrolyzing the resulting acetylated product and neutralizing liberated acetic acid.

(Production of pigment master batches A to G) A polyester resin A and a yellow pigment (CI Pigment Yellow 180) are charged and kneaded in a pressure kneader so that the weight ratio of the resin to the pigment becomes 7: 3. did. The resulting kneaded product was cooled and pulverized by a feather mill to obtain a pigment master batch A. Pigment master batches B to G were obtained in the same manner except that polyester resin A was changed to polyester resins BG.

(Example 1) 93 parts by weight of a polyester resin A, 10 parts by weight of a pigment master batch A, 2 parts by weight of a zinc salicylate complex (E-81: manufactured by Orient Chemical Industries) as a negative charge control agent, oxidized low molecular weight polypropylene ( 1
00TS: Sanyo Chemical Co., Ltd .: softening point 140 ° C, acid value 3.5
After thoroughly mixing 1 part by weight of KOH mg / g) with a Henschel mixer, the mixture was subjected to a twin-screw extruder (PCM-30;
(Ikega Tekko Co., Ltd.) from which the discharge portion was removed, and the mixture was kneaded, and the cooled kneaded material was roughly pulverized with a feather mill. Thereafter, the coarsely pulverized product is finely pulverized by an innomizer (INM-30; manufactured by Hosokawa Micron), and then finely classified by a rotor classifier (Tiplex classifier type 100ATP; manufactured by Hosokawa Micron) to obtain a volume average. 0.1% by weight of toner particles having a particle diameter of 6.2 μm and a particle diameter of twice or more the volume average particle diameter, and 3 of toner particles having a particle diameter of 1/3 or less of the volume average particle diameter 0.8% by number of toner particles were obtained. The circularity of the toner particles was 0.953, and the standard deviation of the circularity was 0.036.

To 100 parts by weight of the toner particles, 0.5 part by weight of hydrophobic silica (TS-500; manufactured by Cabosil) and hydrophobic titanium dioxide (STT30A; manufactured by Titanium Industry)
1.0 part by weight was added and mixed with a Henschel mixer to obtain a yellow toner A.

Examples 2 to 5 In the same manner as in Example 1, except that the polyester resin A was changed to the polyester resins B to E, and the pigment master batch A was changed to the pigment master batches B to E, the yellow toner B was changed in the same manner. ~ E was obtained.

Example 6 A yellow toner F was obtained in the same manner as in Example 2, except that the amount of the oxidized low molecular weight polypropylene was changed to 2 parts by weight.

Example 7 The toner particles obtained in Example 6 were applied to a surface modification device (Hybridization System N).
HS-3 type; Nara Machinery Co., Ltd.)
m for 5 minutes to obtain a yellow toner G in the same manner.

(Comparative Examples 1 and 2)
A jet crusher (IDS: manufactured by Nippon Pneumatic Co., Ltd.) instead of an inomaizer as a crusher for crushing coarse pulverized material
Yellow toners H and I were obtained in the same manner except that the toner was finely pulverized, and that a DS classifier (manufactured by Nippon Pneumatic) was used instead of a rotor classifier as a fine powder classifier. . Comparative Example 3 A yellow toner J was obtained in the same manner as in Example 1, except that the polyester resin A was changed to the polyester resin F and the pigment master batch A was changed to the pigment master batch F.

Comparative Example 4 A yellow toner K was obtained in the same manner as in Example 1, except that the polyester resin A was changed to the polyester resin G and the pigment master batch A was changed to the pigment master batch G.

(Comparative Example 5) I.
Pigment Yellow 180 as C.I. I. A yellow toner L was obtained in the same manner except that the solvent was changed to Solvent Yellow 19.

Comparative Example 6 In Example 1, C.I. I.
Pigment Yellow 180 as C.I. I. Pigment Yellow 133 except that the yellow toner M
I got

Comparative Example 7 In Example 1, C.I. I.
Pigment Yellow 180 as C.I. I. Pigment Yellow 169 except that the yellow toner N
I got

Comparative Example 8 In Example 1, C.I. I.
Pigment Yellow 180 as C.I. I. Pigment Yellow 62, except that Pigment Yellow 62 was used.

(Comparative Example 9) In Example 2, a finely pulverized product was obtained by finely pulverizing a coarsely pulverized product using a jet pulverizer (IDS: manufactured by Nippon Pneumatic Co., Ltd.) instead of an inomaizer as a pulverizing device. The pulverized product was heat-treated at 108 ° C. using a heat treatment apparatus manufactured by Hosokawa Micron Corporation to perform spheroidization. Thereafter, the coarse powder and the fine powder were removed using an elbow jet classifier (manufactured by Nittetsu Mining Co., Ltd.) to obtain toner particles.
100 parts by weight of the toner particles are added to hydrophobic silica (TS-5).
00; manufactured by Cabosil Co., Ltd.) and 1.0 part by weight of hydrophobic titanium dioxide (STT30A; manufactured by Titanium Industry Co., Ltd.) were added and mixed with a Henschel mixer to obtain a yellow toner P.

The toner particles having a volume average particle diameter ((D ₅₀ )) of at least twice the volume average particle diameter of the toners A to P obtained in Examples 1 to 7 and Comparative Examples 1 to 9 ( > 2D ₅₀ )
% Of the content of the toner particles, the number% of the content of the toner particles (<D _50/3 ) having a particle diameter of 1/3 or less of the volume average particle diameter, the average circularity of the toner particles, and the standard deviation of the circularity. The results are shown in Table 2.

[0054]

[Table 2]

(Production of Cyan Toner, Magenta Toner, and Black Toner) I. Pigment Yellow 180 as C.I. I. Pigment Blue 15
A cyan toner was obtained in the same manner except that the toner was changed to -3.
The volume average particle size of the cyan toner is 6.2 μm, and the content of toner particles having a particle size twice or more the volume average particle size is 0.1 μm.
The content of the toner particles having a particle diameter of 1% by weight and 1/3 or less of the volume average particle diameter is 2.9% by number, the average circularity of the toner particles is 0.956, and the standard deviation of the circularity is 0.035. Met.

Further, in Example 2, C.I. I. Pigment Yellow 180 as C.I. I. Pigment Red 184
A magenta toner was obtained in the same manner except that the above was changed. The volume average particle size of the magenta toner is 6.2 μm, and the content of toner particles having a particle size twice or more the volume average particle size is 0.1 μm.
The content of the toner particles having a particle diameter of 1% by weight and not more than 1/3 of the volume average particle diameter is 3.2% by number, the average circularity of the toner particles is 0.955, and the standard deviation of the circularity is 0.036. Met.

In Example 2, C.I. I. Pigment Yellow 180 with carbon black (Mogal L;
A black toner was obtained in the same manner except that the amount was changed to 5 parts by weight (manufactured by Cabot Corporation). The volume average particle diameter of the black toner is 6.4 μm, the content of the toner particles having a particle diameter more than twice the volume average particle diameter is 0.1% by weight, and the volume average particle diameter is 1%.
The content of toner particles having a particle size of / 3 or less was 2.3% by number, the average circularity of the toner particles was 0.959, and the standard deviation of the circularity was 0.037.

The following evaluations were performed on the above toners, and the results are shown in Table 3.

(OHP Translucency and Color Reproducibility of Images with Different Dot Area Ratios) Using a full-color printer described below under normal temperature and normal humidity environment (25 ° C., 60% RH)
Dot area ratio 1 on a 150-line screen on a P sheet
Images of 00%, 50% and 20% were imaged, and the yellow color development when projected by an overhead projector was visually evaluated. A case of vivid color development was evaluated as 、, a case of slight color development was evaluated as Δ, and a case of no color development was evaluated as ×.

The full-color printer used for this evaluation has the configuration shown in FIG. 1, and is driven by an organic photoconductor drum 10 (hereinafter, photoconductor 10) which is rotated in the direction of arrow a in the figure.
, Laser scanning optical system 20, full-color developing device 3
0, an endless intermediate transfer belt 40 that is driven to rotate in the direction of arrow b in the figure, and a paper feed unit 60. Around the photoconductor 10, there are further provided a charging brush 11 for charging the surface of the photoconductor 10 to a predetermined potential and a cleaner 12 having a cleaner blade 12a for removing toner remaining on the photoconductor 10.

The laser scanning optical system 20 is a well-known type having a built-in laser diode, polygon mirror and fθ optical element, and its control unit includes cyan (C), magenta (M), yellow (Y), and black (BK). Each print data is transferred from the host computer. The laser scanning optical system 20 sequentially outputs print data for each color as a laser beam, and scans and exposes the photoreceptor 10. As a result, an electrostatic latent image for each color is sequentially formed on the photoconductor 10.

The full color developing device 30 includes C, M, Y, B
The four color developing units 31C, 31M, 31Y, and 31BK, each containing a one-component developer made of K non-magnetic toner, are integrated, and can be rotated clockwise about a support shaft 81 as a fulcrum. Each developing device has a developing sleeve 32 and a toner regulating blade 34. The toner conveyed by the rotation of the developing sleeve 32 is charged by passing through a pressure contact portion (a regulating portion) between the blade 34 and the developing sleeve 32.

The intermediate transfer belt 40 includes support rollers 41 and 4
2 and endlessly stretched over the tension rollers 43 and 44, and are rotated in the direction of arrow b in FIG. A projection (not shown) is provided on a side portion of the intermediate transfer belt 40. By detecting the projection by the microswitch 45, image forming processes such as exposure, development, and transfer are controlled. The intermediate transfer belt 40 is a rotatable primary transfer roller 4.
6 is in contact with the photoconductor 10. This contact portion is the primary transfer portion T1. The intermediate transfer belt 40 is in contact with a rotatable secondary transfer roller 47 at a portion supported by the support roller 42. This contact portion is the secondary transfer portion T
2

Further, a cleaner 50 is provided in a space between the developing device 30 and the intermediate transfer belt 40. The cleaner 50 has a blade 51 for removing residual toner on the intermediate transfer belt 40. The blade 51 and the secondary transfer roller 47 can be moved toward and away from the intermediate transfer belt 40.

The paper supply unit 60 includes a paper supply tray 61 that can be opened to the front side of the image forming apparatus main body 1, a paper supply roller 62,
And a timing roller 63. The recording sheets S are stacked on a paper feed tray 61, fed one by one in the drawing by the rotation of a paper feed roller 62, and synchronized with an image formed on the intermediate transfer belt 40 by a timing roller 63. To the secondary transfer section. The horizontal conveyance path 65 for the recording sheet is constituted by an air suction belt 66 and the like including the paper feeding section, and a vertical conveyance path 71 provided with conveyance rollers 72, 73, 74 from the fixing device 70 is provided. The recording sheet S is discharged from the vertical conveyance path 71 to the upper surface of the main body 1 of the image forming apparatus.

Here, the printing operation of the full-color printer will be described. When the printing operation is started, the photoconductor 10 and the intermediate transfer belt 40 are driven to rotate at the same peripheral speed, and the photoconductor 10 is charged to a predetermined potential by the charging brush 11.

Subsequently, exposure of the cyan image is performed by the laser scanning optical system 20, and an electrostatic latent image of the cyan image is formed on the photosensitive member 10. This electrostatic latent image is immediately developed by the developing device 31C, and the toner image is transferred onto the intermediate transfer belt 40 in the primary transfer section. Immediately after the end of the primary transfer, the developing device 31M is switched to the developing unit D, and then exposure, development, and primary transfer of the magenta image are performed. Further, switching to the developing device 31Y, exposure and development of a yellow image,
Primary transfer is performed. Further, switching to the developing device 31BK, exposure and development of a black image, primary transfer are performed, and
The toner image is superimposed on the intermediate transfer belt 40 every time the next transfer is performed.

When the final primary transfer is completed, the recording sheet S is sent to the secondary transfer section, and the full-color toner image formed on the intermediate transfer belt 40 is transferred onto the recording sheet S. When the secondary transfer is completed, the recording sheet S is conveyed to the belt-type contact heating and fixing device 70, where the full-color toner image is fixed on the recording sheet S and discharged to the upper surface of the printer body 1.

Incidentally, the image formation is performed by the following method.
550 V, a developing bias voltage of -200 V, a primary transfer bias voltage of 900 V, and a secondary transfer bias voltage of 500 V. Under the setting conditions that the toner adhesion amount of the solid image portion on the recording sheet is 0.7 mg / cm ² , And fixing temperature 1
The test was performed at 60 ° C. In addition, the following fog, hollow,
The transferability and dot reproducibility were evaluated in a low temperature and low humidity environment (1
0 ° C., 15% RH) and high temperature and high humidity environment (30 ° C., 85%)
% RH), and the results of the worse evaluation are shown in Table 3.
It was shown to.

(Fog) A character pattern having a B / W ratio of 5% was printed with a single color of yellow toner using the above-described full-color printer, and the obtained image was visually checked. A sample having no practical problem with fog was evaluated as Δ, and a sample having fog existing over the entire surface and having a practical problem was evaluated as x.

(Empty) Using the above-described full-color printer, a green “E” character in which yellow toner and cyan toner are superimposed is printed. The ones that have image loss but can recognize the green "E" character and have no practical problems. The ones with severe image loss and difficult to recognize the green "E" character. Was evaluated as x.

(Transferability) For an image printed with a single color of yellow toner using the above-described full-color printer, the ratio of the amount of toner adhering on the transfer paper to the amount of toner adhering on the photosensitive drum was determined. , 70
% Or more and less than 80% were evaluated as Δ, and those less than 70% were evaluated as x.

(Dot Reproducibility) A 2-dot halftone image is imaged at 600 dpi, dots are observed with a loupe (50 times), and the dots are reproduced one by one. Small ones are shown as 、, dots and dots are separated and there is no loss, but ones with large variation in dot size are △, each one of two dots is missing,
Those that were stuck together or were not sufficiently reproduced in dots were evaluated as x.

(Light fastness) Images printed with a single color of yellow toner using the above-described full-color printer were irradiated with ultraviolet light for 30 minutes using an ultraviolet irradiation device. Those having no problem were evaluated as Δ, and those with large fading were evaluated as x.

(Heat resistance) 5 g of the toner was placed in a 50 cc glass bottle, and the toner was allowed to stand at 55 ° C. for 24 hours. The toner was checked for cohesiveness. However, those which were easily loosened by external force were evaluated as △, and those which had aggregates and were not easily loosened by external force were evaluated as ×.

[0076]

[Table 3]

The yellow toner F obtained in Example 6 and the cyan toner, magenta toner and black toner obtained in the above-mentioned production example were subjected to 3000 full-color images having a B / W ratio of 6% using the above-mentioned full-color printer.
A printing durability test was performed on the sheets. For the image after the end of printing,
When the evaluation of fog, hollow spots and transferability was carried out, all the ranks were maintained as ○.

[0078]

According to the present invention, a non-magnetic one-component yellow developer excellent in translucency and color reproducibility can be obtained.

Further, according to the present invention, it is possible to obtain a non-magnetic one-component yellow developer having excellent transferability even when a multicolor image is formed.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a full-color printer.

[Explanation of symbols]

10: Photoreceptor drum, 20: Laser optical system, 30: Full color developing device, 40: Intermediate transfer belt, 60: Paper feeding means, 70: Fixing device.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Katsunori Kurose 2-3-113 Azuchicho, Chuo-ku, Osaka City Inside Osaka International Building Minolta Co., Ltd. (72) Hiroyuki Fukuda 2-3-3 Azuchicho, Chuo-ku, Osaka City No. 13 Osaka International Building Minolta Co., Ltd.

Claims (2)

[Claims] 1. A non-magnetic one-component developer used for forming a full-color image for reproducing a multicolor image, wherein the non-magnetic one-component developer has an acid value of at least 1 to 30 KOHmg /
g of a binder resin and a compound classified as Pigment Yellow 180. The toner particles have a negative circularity of 0.94.
, A standard deviation of circularity of 0.045 or less, a weight average particle size of 2 to 9 μm, and a content of toner particles having a particle size of twice or more the weight average particle size in the toner particle size distribution. A non-magnetic one-component developer, wherein the content of toner particles of 2% by weight or less and 1/3 or less of the weight average particle diameter is 5% by number or less. 2. The glass transition point of the binder resin is 5
The non-magnetic one-component developer according to claim 1, wherein the developer has a softening point of 5 to 75 ° C, a number average molecular weight of 2500 to 6000, and a weight average molecular weight / number average molecular weight of 2 to 8.